Linux IMAP, Active Directory with MS Outlook

I'm about to experiment with some email client/server configuration on Linux and would like some of you EExperts to help make sure I'm both sane and don't do something stupid.

I have Linux Slackware64 14.1 system which is configured as a Domain Controller/Active Directory using Samba4. That works great with Window Domain client workstations.

Now, I'd like to get basic email service going.

According to my research, I want IMAP instead of POP3 because (http://en.wikipedia.org/wiki/Internet_Message_Access_Protocol) "IMAP, unlike POP, specifically allows multiple clients simultaneously connected to the same mailbox, and through flags stored on the server, different clients accessing the same mailbox at the same or different times can detect state changes made by other clients."

My experience is limited to Outlook and Exchange on Windows and Sendmail and various clients (mailx, mutt) on Linux.

My questions:

1. Is Dovecot the IMAP server of choice for Linux?

2. If so, it appears (http://en.wikipedia.org/wiki/Comparison_of_mail_servers) that dovecot does IMAP, but not SMTP, therefore I still need an smtp server like Sendmail, right? That same link indicates that Sendmail works with dovecot.

3. If dovecot is best for IMAP, I would prefer using Sendmail for SMTP since I have a lot of experience using it, but also I've already got various milters configured/built for e.g. spam, antivirus, etc. and would prefer to leverage all that. Therefore, can someone point out to me how to integrate Sendmail and dovecot.

4. I would like to use AD Authentication for the Outlook users. Supposedly this can be done with Outlook and IMAP. I haven't checked the Outlook setup to verify this, but I'd appreciate it if someone could confirm this.

5. Here's the confusing bit: even if I can authenticate using Active Directory, I believe Sendmail is still going to want to put SMTP received mail into /var/spool/mail/{username} folders in traditional mbox format. So, do I therefore need to either create a Linux user account for each domain user? Or alternatively, create an alias for each user in in /etc/mail/aliases as:

joe        /var/spool/mail/joe

I assume "yes" I will have to do one or the other, but maybe the answer to #3 will clarify this question.

6. According to what I've read, IMAP is "folder oriented" and the various mail folders a user creates using e.g. Outlook are actually stored on the server, not on the client workstation. How do the messages get from the mbox format created by Sendmail to the complex folder format (dbox?) used by Dovecot's implementation of IMAP. Would this also be explained by #3?

7. Finally, can I take an Outlook pst file and get it to dovecot? I ask this because we have Outlook users with many years of email and these cannot be simply lost or archived.

Thanks for your guidance